Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already mark the tool readOnly, idempotent, and non-destructive, and the description adds substantial behavioral context beyond them: it does not return autofillScript, valuePreview values are masked, externalIsCanonical changes the meaning of submission, requiresPhoneVerification does not apply to the authenticated agent, and canOneClick=false without externalUrl means submit_signup will reject. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long but organized into three labeled sections—when to use, combination chain, and pitfalls—with numbered items. Every sentence carries operational value, from '绝不许瞎编' to '别拿这个字段去劝退用户', and the load-bearing info is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite no output schema, the description tells the agent what the call returns (public details plus my status, current answers, missing required fields), how to chain follow-up tools, and six edge cases that affect downstream behavior. This is complete for safe and correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema covers the only parameter fully (slug minLength 1, described as '活动 slug（取自 list_signup_feed 的 items[].slug）'), so the baseline is 3. The description also references slug in the submit chain, but it adds no new semantic details beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with an explicit trigger ('用户对某一场感兴趣、或准备报名之前调它') and a precise verb+resource: one call returns both public signup details and the caller's signup status. It also differentiates itself by naming related tools in the combination chain, so an agent can separate it from get_signup_gaps, submit_signup, and list_my_signups.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It states exactly when to call and gives a workflow: if viewer.missingRequired is non-empty, ask the user and call submit_signup; if gaps span other sessions, use get_signup_gaps; if already submitted, use list_my_signups. This is explicit when-to-use/alternative guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.